During the forthcoming year we will follow two independent lines of investigation. One of these will be concerned with additional studies of the physical and chemical properties of the soluble and membrane-bound forms of dopamine-beta-hydroxylase. Among the studies to be carried out are the following: binding of flourescent probes and fluorescent spectroscopy to investigate the active site of the enzyme; characterization of cyanogen bromide cleavage peptides by slab gel electrophosis; analysis of the denaturation characteristics of the enzymes, and exact determination of the subunit molecular weights. The second line of investigation is concerned with studies of stimulation-secretion coupling using isolated adrenal cells in culture to identify and sort out molecular events concerned with this event. We will also characterize these cells both morphologically and biochemically during long term maintenance in culture.